DebouncedIn.cpp

00001 #include "DebouncedIn.h"
00002 #include "mbed.h"
00003 
00004 /*
00005  * Constructor
00006  */
00007 DebouncedIn::DebouncedIn(PinName in) 
00008     : _in(in) {    
00009         
00010     // reset all the flags and counters    
00011     _samples = 0;
00012     _output = 0;
00013     _output_last = 0;
00014     _rising_flag = 0;
00015     _falling_flag = 0;
00016     _state_counter = 0;
00017     
00018     // Attach ticker
00019     _ticker.attach(this, &DebouncedIn::_sample, 0.005);     
00020 }
00021   
00022 void DebouncedIn::_sample() {
00023 
00024     // take a sample
00025     _samples = _samples >> 1; // shift left
00026       
00027     if (_in) {
00028         _samples |= 0x80;
00029     }  
00030       
00031     // examine the sample window, look for steady state
00032     if (_samples == 0x00) {
00033         _output = 0;
00034     } 
00035     else if (_samples == 0xFF) {
00036         _output = 1;
00037     }
00038 
00039 
00040     // Rising edge detection
00041     if ((_output == 1) && (_output_last == 0)) {
00042         _rising_flag++;
00043         _state_counter = 0;
00044     }
00045 
00046     // Falling edge detection
00047     else if ((_output == 0) && (_output_last == 1)) {
00048         _falling_flag++;
00049         _state_counter = 0;
00050     }
00051     
00052     // steady state
00053     else {
00054         _state_counter++;
00055     }
00056     
00057    // update the output
00058     _output_last = _output;
00059     
00060 }
00061 
00062 
00063 
00064 // return number of rising edges
00065 int DebouncedIn::rising(void) {
00066     int return_value = _rising_flag; 
00067     _rising_flag = 0;
00068     return(return_value);
00069 }
00070 
00071 // return number of falling edges
00072 int DebouncedIn::falling(void) {
00073     int return_value = _falling_flag; 
00074     _falling_flag = 0;
00075     return(return_value);
00076 }
00077 
00078 // return number of ticsk we've bene steady for
00079 int DebouncedIn::steady(void) {
00080 return(_state_counter);
00081 }
00082 
00083 // return the debounced status
00084 int DebouncedIn::read(void) {
00085     return(_output);
00086 }
00087 
00088 // shorthand for read()
00089 DebouncedIn::operator int() {
00090     return read();
00091 }
00092 
00093